The invention relates to an ink-jet recording apparatus that forms an image on a recording medium by ejecting ink droplets onto the recording medium.
Ink-jet image forming devices, e.g., printers, generally employ at least one ink-jet head which distributes ink supplied from an ink tank to a plurality of pressure chambers contained therein. The ink-jet head selectively applies a pulsed pressure to the pressure chambers and the pressure causes nozzles of the ink-jet head to eject ink droplets onto a recording medium (e.g., paper). In the ink-jet head, ink channels provide ink to the nozzles. The ink channels are extremely narrow, and thus, the ink channels may become clogged with ink. Clogging or blockage of the ink channel is more likely to occur in ink channels that are associated with nozzles which do not regularly eject ink because when ink is maintained in an ink channel, the viscosity of the maintained ink increases. In order to reduce, and preferably prevent, clogging of the ink channels, preliminary ink ejection is performed to eject ink from the nozzles before a printing operation is started, regardless of whether the nozzles are to eject ink during the printing operation.
In serial-type ink-jet printers wherein the ink-jet heads move in a direction substantially perpendicular to a conveying direction of a recording medium, methods for performing preliminary ink ejection are known. For example, in serial-type ink-jet printers, preliminary ink ejection may be performed after the ink-jet heads are moved to a position where the ink-jet heads are not opposite to a conveyor belt that conveys the recording medium. However, line-type ink-jet printers which have a plurality of ink-jet heads arranged such that the longer sides of each ink-jet head extend along a direction substantially perpendicular to a recording medium conveying direction, have become a focus of attention for high-speed printing. In line-type ink-jet printers, the size of the ink-jet printer becomes large if it is designed such that, for preliminary ink ejection, either the ink-jet heads or a conveyor belt is moved so as not be opposite to the other. Japanese Laid-Open Patent Publication No. 2000-272110 discloses an approach for preliminarily ink ejection for a line-type ink-jet printer, in which ink is ejected during preliminary ink ejection onto a preliminary ejection area provided on a conveyor belt.